1. Technical Fields
This invention generally relates to instruments of the type which translate movement into electrical signals and more specifically relates to an instrument using the Hall effect to detect the revolution of a shaft.
2. Background Art
Position sensors are widely used in the automotive industry to measure engine-shaft position in such applications including the electrical movement of vehicle seats, into positions selected by a user, as referred to as power seats. Power seats typically move forward, backward, up, down, and tilt. Position sensors are used to measure how many times a power seat motor shaft turns, which allows the position of the power seat to be calculated. Knowing the position of a power seat allows it to be captured into a memory, storing the position for the user to recall at a later time. The recall of seat positions allows for several users to program preferred seat positions.
Various conventional devices relate to position sensors. Examples of patents pertinent to the present invention include:
Japanese Patent No. A 3,074,812 to Atsushi for ferrite magnetic material;
British Patent No. 990,993 to Craxton for improvements in and relating to electric signal generators;
U.S. Pat. No. 4,570,118 to Tomczak et al. for an angular position transducer including permanent magnets and Hall effect device; and
U.S. Pat. No. 5,712,561 to McCurley et al. for a field strength position sensor with improved bearing tolerance in a reduce space;
each of which is herein incorporated by reference for its pertinent and supportive teachings.
Problems exist with the rotary encoders in the aforementioned references. For instance, rotary encoders are used in close proximity to a DC motor in many automotive applications. Yet, DC motors create electrical noise that interrupts the functioning of rotary encoders. Therefore, there existed a need to provide a rotary encoder that provides electrical noise immunity when working in close proximity to a DC motor.
The foregoing patents reflect the most relevant state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information that may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicants' claimed invention.